Audio: Sam Kamin speaks with Ryan Warner

Partygoers listen to music and smoke marijuana on one of several days of the annual 4/20 marijuana festival, in Denver's downtown Civic Center Park, Saturday April 18, 2015.

(AP Photo/Brennan Linsley)

The Supreme Court decided last week that it won't hear Nebraska and Oklahoma's challenge to marijuana laws in Colorado. The decision leaves the fledgling industry free of any major legal challenges.

Three other suits had been brought in federal district court. Two of the them accused specific marijuana businesses of racketeering or organized crime. In another suit, sheriffs and district attorneys sued Gov. John Hickenlooper for forcing them to break federal laws against marijuana.

Each of those cases has now been declined or dismissed.

Sam Kamin, who teaches criminal and constitutional law at the University of Denver, says that while Colorado's experiment with recreational marijuana has overcome current legal hurdles, it could face a new threat if the next president decides to enforce federal laws that prohibit marijuana.

He spoke with Colorado Matters host Ryan Warner about why each of the of the four challenges failed.

States of Nebraska and Oklahoma v. State of Colorado: Plaintiffs in the case invoked the federal government's right to regulate drugs and interstate commerce. It also said that legal marijuana in Colorado had created an undue burden on Oklahoma and Nebraska, which have had to spend more money on law enforcement as marijuana from Colorado spills over the state borders.

The Supreme Court declined to hear the case, but Justice Samuel Alito and Clarence Thomas dissented. “The plaintiff states have alleged significant harms to their sovereign interests caused by another state,” Justice Thomas wrote.

The shop said that the lawsuit forced it to close, prohibiting the move. Two companies that had done business with the shop settled for a total of $70,000. The lawsuit was dismissed on December 2015 following the settlement.

Sheriffs and prosecutors v. Gov. John Hickenlooper: In what was the most strident legal challenge to recreational marijuana, sheriffs and prosecuters sued the governor for forcing them to break federal laws against marijuana. A federal judge dismissed the case in February with prejudice, meaning it can't be appealed or re-tried.